1. Field of the Invention
The present invention relates to a semiconductor integrated device and a control method thereof. In particular, the present invention relates to a semiconductor integrated device that includes a plurality of functional blocks for carrying out one function, and a control method thereof.
2. Description of Related Art
When resetting a system LSI, since the internal circuits of the system LSI are activated at a time, a large current is instantaneously generated. The current value is proportional to the circuit size. Therefore, along with the increased size of the system LSI, the current generated inside the system LSI also increases at the time of reset. As a result, a power supply voltage drop generated inside the system LSI circuit causes unstable operation, and thereby disabling to reset correctly sometimes.
If the current generated inside the system LSI circuit increases, higher specifications are required for an external power supply circuit of the system LSI in terms of the current variation and a maximum current value at the time of reset. This seriously affects when building the system including such system LSI.
For such problem, Japanese Unexamined Patent Application Publication No. 8-185244 (Hanaoka) discloses a semiconductor integrated device that divides the internal circuits into a plurality of blocks by function and resets the functional blocks by each functional block, and the control method thereof. FIG. 4 illustrates a configuration of a semiconductor integrated device 100 according to a related art. In the semiconductor integrated device 100 of the related art, a plurality of functional blocks KA to KN are controlled by one control system. The semiconductor integrated device 100 includes a selective reset unit 101 which selects and resets the functional block. The selective reset unit 101 measures the number of edge or edge interval of a reset signal, and if the measurement result matches any of predetermined setting values, the selective reset unit 101 resets the functional block corresponding to the matched setting value. At the time of resetting the functional blocks KA to KN, the semiconductor integrated device 100 changes the timing to supply the reset signal to the functional blocks. By selecting the functional blocks KA to KN and resetting the selected functional block, it is possible to prevent activation of the internal circuits at a time, and a large current from flowing inside the internal circuits.